Fix some issues with current docs. (#6588)

docs/index.rst

@@ -28,6 +28,11 @@ The core features include:
    backend/openai_api_embeddings.ipynb
    backend/native_api.ipynb
    backend/offline_engine_api.ipynb
+
+.. toctree::
+   :maxdepth: 1
+   :caption: Advanced Backend Configurations
+
    backend/server_arguments.md
    backend/sampling_params.md
    backend/hyperparameter_tuning.md
@@ -77,4 +82,4 @@ The core features include:
       references/general
       references/hardware
       references/advanced_deploy
-      references/performance_tuning
+      references/performance_analysis_and_optimization